Tools for the stretching or upsetting of sheet metals and profiles



June 9, 1964 w. ECKOLD 3,136,181

TOOLS FOR THE STRETCHING OR UPSETTING 0F SHEET METALS AND PROFILES Flled June 13 1961 United States Patent 3,136,181 TOOLS FOR THE STRETCHING 0R UPSETTING 0F SHEET METALS AND PROFILES Walter Eckold, St. Andreasberg-Sperrluttertal,

' Oberharz, Germany Filed June 13, 1961, Ser. No. 116,854 Claims priority, application Germany June 18, 1960 1 Claim. (Cl. 78-61) The invention relates to a high-speed operated apparatus for the stretching or upsetting of manually controlled sheets and profiles, consisting of a bottom and a top tool with a pair of counterrunning clamping jaws supported by a supporting member.

In order to avoid during the deformation process any wrinkling of the workpiece or an overstretching thereof, it is necessary to maintain the upsetting or stretching movement of the clamping jaws per work cycle as small as possible. Such a restriction of the upsetting respectively stretching movement is also tolerable, since such tools are suitable to perform up to 600 work cycles per minute of upsetting respectively stretching work. In spite of the small counterrunning movement of the upsetting jaws of both about 0.3 to 0.4 mm. a substantial upsetting respectively stretching capacity can be obtained.

The above is, however, only then true when an absolutely uniform pressure application of the tool jaw pair takes place for each work cycle. A non-uniform pressure application of the pair of tool jaws results in that the counterrunning movement of the one jaw pair is initiated earlier than the movement of the other one. This, as above stated, only to a few tenths of a millimeter of the movement of the jaw pair is thus, under certain circumstances already partially or also completely, effected by the one jaw pair before pressure is applied to the other one. If the counterrunning movement for the one jaw pair is initiated too early, then there can be expected only an extremely small upsetting or stretching effect. If the movement of the one jaw pair finishes before the other one commences its counterrunning movement, no effect at all can be obtained. Insofar as the non-uniform working of the tool jaw pair resides in defects in the construction of the tools, these can be overcome by a mechanical finishing and adjusting treatment. The nonuniform working of the tools results, however, from a non-parallel arrangement between the press table and the front surface of the driven machine plunger, overcoming of the defect is difiicult. It is then attempted to remove this source of defect by the underlying of paper or thin metal strips, this being a time consuming, but not always successful, extremely primitive method.

But also in the case of faultlessly working tools and faultless character of the tool contact surfaces in the machine, the upsetting or stretching effect can be rendered more or less questionable in case of non-uniformly performed deformation work on a workpiece, having in its surface dimension irregularly spaced parts with varying material thickness.

In each case the upsetting or stretching effect will be correspondingly small or rendered questionable at all, if in a jaw pair its counterrunning movement is initiated before the movement of the other pair, this resulting from the gripping, non-uniform upsetting, by a particularly thick rendered surface of the material.

Upon most unfavorable coinciding of several of the above illustrated sources of defects an economical output of the tools cannot be achieved without considerable expenditure for refinishing operations which can, however, only then be conducted when the defects of the machine and tool have been clearly recognized. The deviation in the material thickness resulting from non-uniform lice upsetting can, however, neither be overcome by repair work on the tool noron the machine.

It is the object of the present invention to overcome the deficiencies occurring in the known tools of this type and consists in. that the supporting members ofthe one or both tools in the direction of the jaw movement are subdivided into halves, between which a sole type inter-' mediary layer preferably consisting of plastic is inserted in such a manner that pressure forces acting non-uniform on the clamping jaws are automatically equalized.

In a preferred embodiment of the invention the intermediary layer mounted at the one half part of the supporting member, and the thereto facing support surface of the other half of the supporting member, do have in the direction of the jaw movement an interfitting arcuate curvature. The thus obtained rotational movability of the half of the supporting member rigidly connected intermediary layer is restricted in respect'to the other half of the supporting member preferably by means of rubber pads which pads engage partly into the intermediary layer and partly into the adjacent half of the supporting member.

The subject matter of the present invention is illustrated in the drawing in exemplified form and will be described in greater detail further below in connection with this drawing, in which FIGURE 1 is a side elevation showing the apparatus in its entirety and consisting of the bottom and top tool with a pair of other counterrunning clamping jaws,

FIGURE 2 is a side elevation showing the bottom tool in the embodiment according to the present invention on an enlarged scale,

FIGURES 3 and 4 are side and sectional views respectively of further details of the invention.

In the illustrated embodiment the supporting member of the bottom tool is subdivided into two halves or top and bottom members 1 and 2, between which there is arranged a sole type intermediary layer 3 automatically establishing for each work cycle a required equalization of pressure.

The intermediary layer 3 is provided with an upper plane contact surface 3' which is in contact with an also plane surface of the supporting member half 2. The intermediary layer 3 is secured at this supporting member half 2, e.g. by means of a screw 4, while laterally inserted pins 5 safely prevent a rotation.

The lower contact surface 3" of the intermediary layer 3 is provided with an arcuate curvature in the direction of movement of the clamping jaw pair 6, the counterrunning movement of which is effected in known manner by inclined arranged laminas or rollers 7, while the center of the curvature radius is at the upper edge of the clamping jaws 6 in the center between the jaws.

The curved contact surfaces 3 of the intermediary layer 3 closely joints the respective concave machined upper support surface of the lower supporting member half 1.

As indicated in FIG. 2 the radii of the curved contacting surfaces 3" of the bottom base member 1 and the intermediate sole-type layer 3, are indicated by the radius line with arrow showing the center between the two spaced clamping jaws 6 at the top surface thereof. These curved contacting surfaces are mating with each other as clearly shown in FIGS. 1 to 3 of the drawing.

The thus obtained rotational movability of the upper supporting member half in respect to the lower one is maintained restricted in that in recesses of the intermediary layer and the lower supporting member half 1 there are inserted rubber pads 8 permitting the lost motion of the supporting member halves required for the pressure equalization.

The intermediary layer 3 permits a rotary motion along the contact surface 3 relative to the lower supporting member half 1 to permit equalization of non-uniform pressure forces acting on the clamping jaws.

Because of silencing reasons to a certain degree elastic plastics find application as materials which in addition thereto suitably do have self-lubricating properties.

What I claim is:

Die elements for a machine for stretching or upsetting sheet metal comprising a top tool, a bottom tool, each tool having a pair of relatively movable and spaced clamping jaws which are adapted to contact the sheet metal for the stretching or upsetting operation, a top supporting member on which the pair of spaced clamping jaws for the bottom tool are mounted, a bottom base member, and an intermediate sole-type layer between the top supporting member and the bottom base member secured on the top supporting member, said bottom base member and the intermediate sole-type layer having mating arcuate curved contacting surfaces, both having radii with a common center between the two spaced clamping jaws at the top surface thereof of the bottom tool, and a plurality of rubber pads mounted between the bottom base member and the intermediate sole-type layer, each rubber pad being mountedpartly in the bottom base member and the sole-type layer to restrict the rotational movability, and said intermediate sole-type layer being composed of a plastic material whereby pressure forces acting non-uniformly on the clamping jaws are automatically equalized.

References Cited in the file of this patent UNITED STATES PATENTS 637,024 Penwell Nov. 14, 1899 1,988,150 Austin Jan. 15, 1935 2,346,088 Shobert Apr. 4, 1944 2,371,435 -Galorneau Mar. 13, 1945 2,636,433 Wennberg Apr. 28, 1953 2,863,344 Barnes Dec. 9, 1958 2,867,141 Eckold 1.. 1 Jan. 6, 1959 2,911,862 Eckold Nov. 10, 1959 FOREIGN PATENTS 1,130,935 France Feb. 13, 1957 643,782 Germany Mar. 25, 1937 

